• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.196-197
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• 2005

Cathodic protection is one of the successful ways to prevent corrosion of steel structures in marine environments. The unique feature of cathodic protection in seawater is the formation of calcareous deposits on cathodic metal surface. The formation principles of calcareous deposit seawater had been known for a long time. That is, cathodic reduction reactions associated with cathodic protection in seawater generate $OH^-$ at the metal surface in accordance with the formular ; 1/2 $O_2$ + $H_2O$ + $2e^-$ $2OH^-$ and $2H_2O$ + $2e^-$ ${\rightarrow}$ $H_2$ + $2OH^-$. These reactions increase the pH at the metal / seawater interface. The high pH causes precipitation of $Mg(OH)_2$ and $CaCO_3$ in accordance with the formular ; $Mg^{2+}$ + $2(OH)^-$ ${\rightarrow}$ $Mg(OH)_2$ and $Ca^{2+}$ + $HCO_3^-$ + $OH^-$ ${\rightarrow}$ $H_2O$ + $CaCO_3$. These are typically the main compounds in calcareous deposits. It obviously has several advantages compared to the conventional coatings, since the environment-friendly calcareous deposit coating is formed by the elements($Mg^{2+}$, $Ca^{2+}$) naturally present in seawater. In this study, environmental friendly calcareous deposit films were prepared on steel plates by electro plating technic in natural seawater. The influence of current density on composition ratio, structure and morphology of the coated films were investigated by scanning electron microscopy formation process of calcareous deposits films in natural seawater. And we confirmed the properties of all the films can be improved greatly by controlling the material structure and morphology with effective use of the electroplating method in natural seawater.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.437-446
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• 1999

Porphyromonas endodontalis(P. endodontalis) is one of the important causative bacteria of pulpal and periapical disease. P. endodontalis has lipopolysaccharide(LPS) and it plays a major role in stimulating the synthesis and release of cytokines from immune cells and prostaglandin $E_2$ from host cells. The purpose of this study is to prepare LPS from P. endodontalis and to evaluate the effect of LPS on membrane permeability of fibroblast. P. endodontalis ATCC 35406 was cultured in anaerobic condition, and LPS was extracted. LPS was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Human periodontal ligament cell, colon fibroblast(CCD-18Co, KCLB 21459) and skin fibroblast(Detroit 551, KCLB 10110) were perfused with 0.01% P. endodontalis LPS solution, high concentration of $K^+$ solution and $Ca^{2+}$-free solution, $Ca^{2+}$ concentration ratio was measured by microfluorometry. 1. Intracellular $Ca^{2+}$ concentration was not changed in human periodontal fibroblast and skin fibroblast(Detroit 551) stimulated by P. endodontalis LPS. 2. Intracellular $Ca^{2+}$ concentration was increased in colon fibroblast(CCD-18Co) stimulated by P. endodontalis LPS. 3. Colon fibroblast(CCD-18Co) has voltage dependent $Ca^{2+}$ channel activated by high concentration of $K^+$ solution. 4. P. endodontalis LPS has no effect on the increase of intracellular $Ca^{2+}$ concentration during perfusion of $Ca^{2+}$-free solution.

• Childhood Kidney Diseases
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• v.15 no.2
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• pp.146-153
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• 2011

Purpose : Hypercalciuria has been suggested to be involved in the pathogenesis of nocturnal enuresis associated with polyuria. We have measured the amount of calcium excretion in the urine from children with monosymptomatic nocturnal enuresis and studied the association with enuresis. Methods : Thirty-six children (20 males and 16 females, age 5 to 15.6 years) presenting with monosymptomatic nocturnal enuresis were recruited for this study. Results : Among 36 patients, 6 patients had hypercalciuria, providing a 16.7% frequency. The mean Ca/Cr ratio of hypercalciuria group showed $0.23{\pm}0.10$ on daytime, and $0.33{\pm}0.10$ on nighttime showing higher values in nighttime, but it was not statistically significant. Average 24 hour calcium excretion was 8.95 mg/kg. Night/day time urine volume ratio in hypercalciuria group was $0.87{\pm}0.20$, and that in normocalciuria group was $0.81{\pm}0.33$, also showing no difference. Daytime Ca/Cr ratio and nighttime Ca/Cr ratio from all enuresis patients showed a significant correlation (P=0.0001). However, Ca/Cr ratio between daytime and nighttime urine volume had no significant correlation, respectively (daytime P=0.08; nighttime P=0.07). Also, daytime and nighttime Na concentration, urea concentration, and osmolality also had no significant correlation with urine Ca/Cr ratio, respectively. Conclusion: Hypercalciuria shown in some of enuresis patients is not directly caused by primary monosymptomatic nocturnal enuresis.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.29-37
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• 2018

In this study, optimum extraction conditions for phosphorus recovery from sewage sludge ash(SSA) were investigated. For this purpose, an experiment was conducted to determine optimal recovery conditions for Ca-P type phosphorus by using calcium component in the recycled aggregate residue. The phosphorus content of sewage sludge ash was confirmed to be 5.0 %. When $H_2SO_4$ was used as an extract, concentration of 1 N $H_2SO_4$, L/S ratio of 10, and extraction time of 30 min were found to be the optimal extraction conditions. Phosphorus was extracted by using optimal extraction conditions, and then the heavy metals eluted with phosphorus were removed using 1~20 g of cation exchange resin. In 20 g of cation exchange resin, Fe 71.3%, Cu 82.4%, Zn 79.9%, and Cr 15% were removed. After that, the mixing ratio of the calcium extract obtained from the recycled aggregate residue (RAR) was changed to 1:1, 1:5, 1:10. The pH of the SSA to RAR mixture was adjusted to 2, 4, 8 and 12 by the addition of 5 N NaOH to the mixture of 1:5, and the phosphorus was recovered as Ca-P type precipitate. The optimum pH was 8. When recycled aggregate residues were used, the weight of calcium phosphate increased, but the amount of wastewater generated also increased. Therefore, it was concluded that the use of recycled aggregate residue was not economically feasible.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.1
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• pp.101-110
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• 2019

The aim of this study was to evaluate and compare the microstructural properties and mineralization quality of mesiodens with permanent and primary central incisors. Fifteen mesiodens, permanent and primary central incisors were collected. The enamel rod diameter and enamel thickness were observed and measured using field emission scanning electron microscope (FE-SEM). Chemical composition of the enamel was analyzed using energy dispersive X-ray spectrometer (EDS). The measurements were then assessed using the one-way ANOVA and Tukey test. There was no statistically significant difference in the enamel rod diameter between mesiodens and permanent central incisors. However, enamel rods of primary central incisors were smaller than remaining two groups. The thickness of enamel was thick in order of permanent central incisors, mesiodens, primary central incisors. In the composition analysis using EDS, there was no difference in the Ca/P ratio and Ca/C ratio between mesiodens and permanent central incisors, but small in primary central incisors. In conclusion, the microstructural properties of mesiodens were more similar to those of permanent central incisors compared to primary central incisors. Futher, the mineralization quality of mesiodens did not differ significantly from that of permanent central incisors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.437-442
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• 1993

Soybean curds were made from the mixture of soybean milk and cow's milk (raw milk) at the ratio of 10, 20, 30, 40, 50% (v/v), and then the general composition and mineral content, pH, yield, firmness by sensory evaluation and amino acid composition were investigated. As cow's milk addition increased, total sugar crude fat, crude protein, ash content, firmness, weight and volume of the soybean curd were increased. Whereas moisture content decreased, $Ca^{＋＋}$, $K^{＋}$, and Na$^{＋}$ were increased, but $Mg^{＋＋}$ and Fe$^{＋＋}$ decreased. In sensory evaluation, color (white), firmness, flavor, and taste were higher than those of control as cow's milk increased. By adding cow's milk at the ratio of 10, 20, 30, 40%, and 50%, sulfur containing amino acid content such as methionine and cystine were enriched 1.31, 1.58, 1.67, 1.85, and 1.95 times, respectively.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.631-640
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• 2018

The application of an oxy-combustion circulating fluidized bed combustor (Oxy-CFBC) for low grade coals has recently developed in the world to meet the continuous increase of energy demand and to achieve the reduction of greenhouse gases. Since demo plants for Oxy-CFBC have been developed, the combustion properties of Oxy-CFBC in various operation conditions, such as gas flow rates, combustion temperature, fuel, and so on, should be investigated to develop design criteria for a commercial Oxy-CFBC. In this study, a computational simulation tool for Oxy-CFBC was developed on the basis of the IEA-CFBC (International Energy Agency Circulating Fluidized Bed Combustor) model. Simulation was performed under various conditions such as reaction temperature ($800^{\circ}C{\sim}900^{\circ}C$), oxygen contents (21%~41%), coal feeding rate, Ca/S mole ratio (1.5~4.0), and so on. Simulation results show that the combustion furnace temperature is higher in oxy 1 than air fired. However, the temperature gradient tended to decrease with increasing oxy mixing percent. In case of $SO_x$, the higher the Ca/S mole ratio and oxy mixing percent, the higher the desulfurization efficiency.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.90-98
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• 2002

The effects of swirl and combustion parameters on the performance and emission in a turbo-charged D.I. diesel engine of the displacement 9.4L were studied experimentally in this paper. Generally the swirl in the combustion process of diesel engine promotes mixing of the injection fuel and the intake air. It is a major factor to improve the engine performance because the fuel consumption and NO$_{x}$ is trade-off according to the high temperature and high pressure of combustion gas in a turbocharged D.I. diesel engine, it's necessary to thinking over the intake and exhaust system, the design of combustion bowl and so on. In order to choose a turbocharger of appropriate capacity. As a result of steady flow test, when the swirl ratio is increased, the mean flow coefficient is decreased, whereas the gulf factor is increased. Also, through engine test its can be expected to meet performance and emissions by optimizing the main parameter's; the swirl ratio is 2.43, injection timing is BTDC 13$^{\circ}$ CA, compression ratio is 16, combustion bowl is re-entrant 5$^{\circ}$, nozzle hole diameter is $\Phi$0.28*6, turbocharger is GT40 model which are compressor A/R 0.58 and turbine A/R 1.19.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.836-840
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• 2007

This study was conducted to investigate mineral contents of commercial powdered infant formula for obtaining basic data on infant nutrition. 11 Commercial infant formula based on cow's milk were collected and the contents of macro minerals (calcium, phosphorous, sodium, potassium and magnesium) and trace minerals (iron, zinc and copper) were compared with Dietary Reference Intakes for Koreans (KDRIs). The overall mineral contents in 100 g and in 100 kcal of infant formula satisfied the recommended formula regulation and Codex. In infant formula during 0-5 monthly age, calcium, phosphorous, sodium, potassium, magnesium, zinc and copper could supply 233.1%, 273.5%, 156.7%, 142.0%, 150.8%, 209.3%, 171.1% of recommended daily mineral intakes, respectively. The content of iron in 0-5 monthly age formula supplied2842.6% of recommended daily iron intakes. In infant formula during 6-11 monthly age, calcium, phosphorous, potassium, magnesium, iron, zinc and copper satisfied their recommended daily intakes. However, sodium only supplied 76.6% of its recommended daily intake. Intake ratio between Ca/P, Ca/Mg, Ca/Fe, Na/K and Zn/cu in infant formula during 0-5 monthly age were 1.7±0.2, 11.0±2.4,64.9±10.0, 0.3±0.1, and 9.6±1.0, respectively. Intake ratio between Ca/P, Ca/Mg, Ca/Fe, Na/K and Zn/cu in infant formula during 6-11 monthly age were 1.7${\pm}$0.2, 12.9${\pm}$1.5, 80.1${\pm}$13.8, 0.3, and 9.4${\pm}$1.1,respectively. From this study, evaluation of mineral contents of commercial infant formula was established, which could strengthen the basic information on infant nutrition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.727-732
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• 2006

The object of this study was to investigate the influence of composition and concentration of electrolyte, ratio of cation to anion exchange resin of mixed ion exchange column in the performance of ion exchange. Also this work examined the removal capability of suspended solids by ion exchange resin and the effect of particule on the characteristics of ion exchange. Breakthrough time was extended as the amount of ions and particles present in liquid was decreased. The case of anion, the breakthrough sequence is $Cl^{-}, but the case of cation, the breakthrough sequence is $Na^{+}. As for the ratio of cation to anion exchange resin of 1:2, the breakthrough time was prolonged compared with that of 1:1 and 1:3. For the electrolyte of equal concentration containing suspended solid, breakthrough time was contracted less than 20%. It results in the increase in the removal capacity of cation exchange resin. For the higher ratio of cation exchange resin, suspended solids are shorten the cation's breakthrough time so that the runtime of ion exchange resin tower is increased.